In all types of stator construction, the central iron core is constructed from thin coated steel laminations stacked together. By making the coated laminations very thin the resistivity of the steel sheet itself is high and surface insulation of laminations is complete, reducing the eddy current losses through the core. These steel laminations vary in thicknesses from between 0.2 mm to 0.5 mm. The laminations are electrically insulated from each other by a very thin coating of insulating varnish or the like.